This invention relates generally, as indicated, to inspection hole covers for coke ovens, also commonly referred to as flue caps, and more particularly to inspection hole covers or flue caps which are relatively non-magnetic, light in weight, well insulated, and of relatively long life.
Modern coking facilities used in the steel making industry normally include a battery of coke ovens arranged in side-by-side relation with combustion chambers interposed between pairs of ovens. Along the top of each oven are a plurality of spaced-apart charging holes for charging the ovens with coal, which charging holes are provided with covers during the coking process. A series of smaller diameter holes is also provided in the top of each combustion chamber for inspection purposes, i.e., for inspecting the adjacent oven walls for bulges, leaks, etc., as well as the combustion chambers themselves for obstructions or damage. Also, during the coking process, selected inspection hole covers are periodically removed to make temperature checks and immediately put back in place to prevent escape of the hot combustion gases and to preclude entry of foreign material into the combustion chambers.
In modern coking facilities, larry cars, operating between an overhead coal storage bin and the ovens on a track supported by the battery of ovens, are employed to charge the ovens. The larry cars are usually provided with charging hoppers corresponding in number to the number of charging holes of each oven. In addition, the larry cars are usually provided with a corresponding number of magnetic lifts for picking up and replacing the charging hole covers during the charging operation. Accordingly, the charging hole covers are magnetic to permit their removal by the magnetic lifts.
Heretofore, the inspection hole covers have been made from solid cast iron which has known magnetic properties. From time to time during charging of the ovens, the inspection hole covers have sometimes been inadvertently removed by the magnetic lifts resulting in their loss and/or inconvenience to the oven operators. In addition, the cast iron flue caps or inspection hole covers have been somewhat difficult to handle because of their weight and shape. Also, the cast iron inspection hole covers have been subject to corrosion with consequent reduction in their useful life.